Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 323
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Adv Mater ; : e1907365, 2020 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-32022975

RESUMO

Tumor-lymph node (LN) metastasis is the dominant prognostic factor for tumor staging and therapeutic decision-making. However, concurrently visualizing metastasis and performing imaging-guided lymph node surgery is challenging. Here, a multiplexed-near-infrared-II (NIR-II) is reported in vivo imaging system using nonoverlapping NIR-II probes with markedly suppressed photon scattering and zero-autofluorescence, enabling visualization of the metastatic tumor and the tumor metastatic proximal LNs resection. A bright and tumor-seeking donor-acceptor-donor (D-A-D) dye, IR-FD, is screened for primary/metastatic tumor imaging in the NIR-IIa (1100-1300 nm) window. This optimized D-A-D dye exhibits greatly improved quantum yield of organic D-A-D fluorophores in aqueous solutions (≈6.0%) and good in vivo performance. Ultrabright PbS/CdS core/shell quantum dots (QDs) with dense polymer coating are used to visualize cancer-invaded sentinel LNs in the NIR-IIb (>1500 nm) window. Compared to clinically used indocyanine green, the QDs show superior brightness and photostability (no obvious bleaching even after continuous laser irradiation for 5 h); thus, only a picomolar dose is required for sentinel LNs detection. This combination of dual-NIR-II image-guided surgery can be performed under bright light, adding to its convenience and appeal in clinical use.

2.
J Sex Med ; 2020 Feb 06.
Artigo em Inglês | MEDLINE | ID: mdl-32037229

RESUMO

BACKGROUND: Although abnormal sympathetic nerve system (SNS) activity has been demonstrated in the pathogenesis of ejaculation disorders, few data are available on its underlying mechanism. AIM: To investigate whether differences in ejaculatory behavior of rats were associated with the state of SNS activity and gamma-aminobutyric (GABA) receptor expressions in the paraventricular nucleus (PVN) of the hypothalamus and the effects of GABA receptors in the PVN on ejaculatory behavior. METHODS: Based on ejaculatory performance, Sprague-Dawley rats were divided into "sluggish," "normal," and "rapid" ejaculators. PVN microinjection was performed to evaluate the role of GABA receptors on sexual behavior. OUTCOMES: The outcomes include differences in expression and distribution of GABA receptors and norepinephrine level among the 3 groups and changes in copulation behavior parameters after PVN microinjection. RESULTS: Compared with "normal" rats, the "rapid" group ejaculated more times with shorter latency (P < .001, P < .001) and had lower expression and distribution of both GABA-A and GABA-B receptors, while the opposed results appeared in the "sluggish" group. The norepinephrine level was successively increased among "sluggish," "normal," and "rapid" rats (P < .001) and correlated with ejaculation frequency (r = 0.896, P < .001) and ejaculation latency (r = -0.835, P < .001). In addition, bilateral microinjection of the GABA-A and GABA-B receptor agonist (isoguvacine and baclofen) into the PVN both significantly prolonged the intromission latency and inhibited ejaculation, which could be blocked by antagonist gabazine and CGP-35348, respectively. Vigabatrin, the GABA-transaminase inhibitor, caused a significantly reduced ejaculation frequency and extended ejaculation latency in rats, which could be offset by simultaneous injections of gabazine and CGP-35348. CLINICAL IMPLICATIONS: Our findings provide new understanding about GABA receptors in the PVN on sexual behavior and enhance the comprehension of neurobiological mechanisms involved in premature ejaculation. STRENGTHS & LIMITATIONS: Our results have indicated that GABA receptors in the PVN may inhibit ejaculation through restraining the activity of SNS. However, our study did not analyze the changes of GABA receptors in other brain areas, which needs further study. CONCLUSION: Ejaculation behaviors in male rats are associated with SNS activity and could be regulated by GABA receptors in the PVN, which may be of assistance in the treatment of ejaculation disorders in the future. Zhang QJ, Yang BB, Yang J, et al. Inhibitory Role of Gamma-Aminobutyric Receptors in Paraventricular Nucleus on Ejaculatory Responses in Rats. J Sex Med 2020;XX:XXX-XXX.

4.
Artigo em Inglês | MEDLINE | ID: mdl-32056337

RESUMO

The crosslink-enhanced emission effect was first proposed to explore the strong luminescence of non-conjugated polymer dots only possessing either non- or weakly-emissive sub-luminophores. Interesting phenomena in recent research indicate such enhancement caused by extensive crosslinking appears in diverse luminescent polymers with sub-luminophores (electron-rich hetero-atomic moieties) or luminophores (conjugated π domains). This enhancement can promote the emission from non-luminous to luminous, weakly-luminous to strongly-luminous and even converting the pathway of radiative transitions. The concept of the crosslink-enhanced emission effect should be updated and extended to an in-depth spatial effect, such as electron overlap and energy splitting in confined domains by effective crosslinking, more than initial immobilization. This minireview outlines the development of the crosslink-enhanced emission effect from the perspective of the detailed classification, inherent mechanism and applicable systems. An outlook on the further exploration and application of this theory are also proposed.

5.
Adv Mater ; 32(2): e1905927, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31782568

RESUMO

Optical biosensors, especially those based on plasmonic structures, have emerged recently as a potential tool for disease diagnostics. Plasmonic biosensors have demonstrated impressive benefits for the label-free detection of trace biomarkers in human serum. However, widespread applications of these technologies are hindered because of their insufficient sensitivity, their relatively complex chemical immobilization processes, and the use of prism couplers. Accordingly, a sandwiched plasmon ruler (SW-PR) based on a Au nanohole array with ultrahigh sensitivity arising from the plasmonic coupling effect is developed. Highly confined surface charges caused by Bloch wave surface plasmon polarizations substantially increase the coupling efficiency. This platform exhibits thickness sensitivity as high as 61 nm nm-1 and can detect at least 200 000-fold lower analyte concentrations than a nanowell sensing platform with the same wavelength shift. Additionally, the sandwiched plasmonic biosensor allows precise and label-free testing of clinical biomarkers, namely C-reactive protein and procalcitonin, in patient serum samples without requiring a sophisticated prism coupler, extra antibodies, or a chemical immobilization technique. This study yields new insight into the structural design of plasmon rulers and will open exciting avenues for disease diagnosis and therapy follow-up at the point-of-care.

6.
Langmuir ; 36(3): 789-795, 2020 Jan 28.
Artigo em Inglês | MEDLINE | ID: mdl-31815486

RESUMO

We report a facile yet general in situ seed-mediated method for the synthesis of polymer-grafted gold nanoparticles with narrow size distributions (<10%), accurately tunable sizes, and excellent colloidal stability. This method can be extended to a broad range of types and molecular weights of polymer ligands. Nanoparticles with different shapes can also be prepared by using preformed shaped nanoparticles directly as the seeds.

7.
Acta Biomater ; 102: 394-402, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31809883

RESUMO

A retrograde transportation nerve probe, Au nanodots-cholera toxin B subunit (AuNDs-CTB), are prepared and fully characterized, which emit bright red fluorescence and show high quantum yield (7.2%) and good stability. The fluorescence emitted by the AuNDs is constant across a wide pH range (4-10) and after prolonged UV irradiation (>4 h). Previously, CTB has shown targeting characteristic for nerve cells with high sensitivity and effectiveness. After linking CTB to AuNDs through amidation reactions, AuNDs-CTB are obtained with excellent fluorescence property, nerve target characteristic, and, particularly, neural retrograde transportation feature. The red emission of the AuNDs-CTB is well distinguished from the blue autofluorescence of normal tissues, which provides potential for detection by naked eyes. Further, the fluorescence emission intensity maintains for 10 days in vivo, suggesting great utility for long-time monitoring and sensing of the nerve tissue. Furthermore, the AuNDs-CTB with bright red fluorescence can travel through the peripheral nerve to the spinal cord rapidly by retrograde transportation. The transportation occurs for a long distance (>5 cm) within only 2 days after injection of the AuNDs-CTB into the sciatic nerve. The present study exhibits a novel method for nerve visualization and drug delivery. STATEMENT OF SIGNIFICANCE: Au nanodots (AuNDs) conjugated with cholera toxin subunit B (CTB) have been developed for nerve labeling and neural retro-transporting. The red fluorescence from AuNDs-CTB is stable in vitro (pH 4-10 and 4 h UV irradiation) and in vivo (for a long time, more than 10 days). When injecting AuNDs-CTB into the sciatic nerve located at the midpiece of the thigh, the targeted nerve emits bright red fluorescence under UV light. Furthermore, the nerve can retrograde transport the AuNDs-CTB to the spinal cord for a distance of more than 5 cm just in 2 days. This work exhibits a novel method for nerve visualization by naked eyes and demonstrates the potential for intraoperative navigation.

9.
Artigo em Inglês | MEDLINE | ID: mdl-31830863

RESUMO

INTRODUCTION: A key obstacle in the creation of engineered cardiac tissues of clinically relevant sizes is limited diffusion of oxygen and nutrients. Thus, there is a need for organized vascularization within a 3D tissue environment. Human induced pluripotent stem cell (hiPSC) derived early vascular cells (EVCs) have shown to improve organization of vascular networks within hydrogels. We hypothesize that introduction of EVCs into 3D microtissue spheroids will lead to increased microvascular formation and improve spheroid formation. METHODS: HiPSC derived-cardiomyocytes (CM) were co-cultured with human adult ventricular cardiac fibroblasts (FB), and either human umbilical vein endothelial cells (HUVEC) or hiPSC-derived EVCs for 72 hours to form mixed cell spheroids. Three different groups of cell ratios were tested: Group 1 (control) consisted of CM:FB:HUVEC 70:15:15, Group 2 consisted of CM:FB:EVC 70:15:15 and Group 3 consisted of CM:FB:EVC 40:15:45. Vascularization, cell distribution, and cardiac function were investigated. RESULTS: Improved microvasculature was found in EVC spheroids with new morphologies of endothelial organization not found in Group 1 spheroids. CMs were found in a core-shell type distribution in Group 1 spheroids, but more uniformly distributed in EVC spheroids. Contraction rate increased into Group 2 spheroids compared to Group 1 spheroids. CONCLUSION: The triculture of CM, FB and EVC within a multicellular cardiac spheroid promotes microvascular formation and cardiac spheroid contraction.

10.
Adv Sci (Weinh) ; 6(23): 1901316, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31832313

RESUMO

Despite the various synthesis methods to obtain carbon dots (CDs), the bottom-up methods are still the most widely administrated route to afford large-scale and low-cost synthesis. However, as CDs are developed with increasing reports involved in producing many CDs, the structure and property features have changed enormously compared with the first generation of CDs, raising classification concerns. To this end, a new classification of CDs, named carbonized polymer dots (CPDs), is summarized according to the analysis of structure and property features. Here, CPDs are revealed as an emerging class of CDs with distinctive polymer/carbon hybrid structures and properties. Furthermore, deep insights into the effects of synthesis on the structure/property features of CDs are provided. Herein, the synthesis methods of CDs are also summarized in detail, and the effects of synthesis conditions of the bottom-up methods in terms of the structures and properties of CPDs are discussed and analyzed comprehensively. Insights into formation process and nucleation mechanism of CPDs are also offered. Finally, a perspective of the future development of CDs is proposed with critical insights into facilitating their potential in various application fields.

11.
Opt Express ; 27(22): 31348-31361, 2019 Oct 28.
Artigo em Inglês | MEDLINE | ID: mdl-31684369

RESUMO

A spaceborne limb hyperspectral imager for ozone detection is designed and developed. The hyperspectral imager can provide the limb hyperspectral radiances images with wide-band and large dynamic range. It is composed of an off-axis parabolic telescope and prism dispersive off-axis aspheric spectrometer, and large dynamic range detection can be realized by using a band-attenuation filter. The spectral range is from 280nm to 1000nm, the field of view is 2.4° (limb vertical direction) × 0.02° (horizontal direction), and the focal length is 69mm. The design results meet the requirements of image quality and have the characteristics of small volume and light weight, thereby making it especially suitable for the application of space remote sensing unlike existing methods that utilize complicated scanning mirror and multiple color separators. The limb hyperspectral imager is measured and calibrated on ground. It detected limb hyperspectral radiances on Tiangong-2 spacecraft of China.

12.
Nanoscale ; 11(45): 21953-21963, 2019 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-31709429

RESUMO

Gene therapy is one of the most common and effective ways for the regeneration of defective bone tissue, but even highly efficient gene delivery vectors are insufficient. In this study, bone morphogenetic protein-2 plasmid (pBMP-2) was encapsulated by polyethylenimine-modified porous silica nanoparticles (PPSNs), which were synthesized via an ethyl ether emulsion method. Owing to the high specific surface area and high absorption characteristics, low cytotoxicy PPSNs can efficiently load and protect pBMP-2. The resulting PPSN/pBMP-2 can transfect MC3T3-E1 cells effectively to promote osteogenic differentiation and increase calcium deposition in vitro. Interestingly, the mass of calcium deposition nodules decreased dur to the presence of an autophagy inhibitor, demonstrating that PPSNs stimulated the autophagy pathway. Because of their excellent biocompatibility, high transfection efficiency, and ability to stimulate autophagy, the as-prepared PPSN/pBMP-2 could efficiently transfect local cells in a defect area in vivo. Micro-computed tomography and histological images demonstrated that PPSN/pBMP-2 could efficiently promote new bone formation in a 5 mm sized rat calvarial defect model. Taken together, our newly synthesized PPSNs could efficiently carry pBMP-2 and deliver it to the target cells as well as stimulating the autophagy pathway, resulting in significant osteogenic differentiation and bone regeneration.

13.
Biomater Sci ; 7(12): 5414-5423, 2019 Nov 19.
Artigo em Inglês | MEDLINE | ID: mdl-31633717

RESUMO

Carbon dots are a new kind of nanomaterial which has great potential in biomedical applications. Previously, we have synthesized novel Zn2+-passivated carbon dots (Zn-CDs) which showed good osteogenic activity in vitro. In this study, we will further investigate the osteogenic effects of Zn-CDs in vivo which is essential before their clinical use. Herein, Zn2+-passivated carbon dots (Zn-CDs) are prepared and characterized as previously reported. Then, the optimum dose for inducing osteoblasts was evaluated by MTS assay, intracellular reactive oxygen species (ROS) detection, alkaline phosphatase (ALP) activity test and alizarin red staining in vitro. Finally, a 5 mm diameter calvarial bone defect model was created in rats and Zn-CDs were applied for repairing the critical bone defect. It was shown that zinc gluconate (Zn-G) and Zn-CDs promoted the survival of bone marrow stromal cells (BMSCs) when the zinc ion concentration was 10-4 mol L-1 (Zn-G: 45.6 µg mL-1) and 10-5 mol L-1 (Zn-CDs: 300 µg mL-1) or below respectively. With regard to the osteogenic capability, the ALP activity induced by Zn-CDs was significantly higher than that by Zn-G. Besides, the results of alizarin red staining showed that the area of calcified nodules was increased in a dose-dependent manner in the Zn-CD group. Moreover, there were more calcium nodules in the Zn-CD group than in the Zn-G group at the same concentration of Zn2+ (10-5 mol L-1). Taken together, Zn-CDs achieved the highest osteogenic effect at the concentration of 10-5 mol L-1 without affecting cell proliferation in long-term stimulation. Importantly, the volume of new bone formation in the Zn-CD group (6.66 ± 1.25 mm3) was twice higher than that in the control group (3.33 ± 0.94 mm3) in vivo. Further histological evaluation confirmed the markedly new bone formation at 8 weeks in the Zn-CD group. The in vitro and in vivo experiments revealed that Zn-CDs could be a new predictable nanomaterial with good biocompatibility and fluorescence properties for guiding bone regeneration.

14.
Lab Chip ; 19(20): 3368-3374, 2019 Oct 09.
Artigo em Inglês | MEDLINE | ID: mdl-31549119

RESUMO

Ultramicro-volume syringes were fabricated by integrating micro-nanostructure arrays in microchannels for quantitatively dispensing sub-picoliter volumes of liquids. Using this system, liquids were dispensed in volume increments as low as 0.5 pL with 96% accuracy. Specifically, the controllable synthesis of nanocrystals was achieved using a lab-on-chip platform that was integrated with the syringes.

15.
Biomater Sci ; 7(12): 4990-5001, 2019 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-31482868

RESUMO

Chemotherapy is one of the most common and effective ways for the clinical treatment of tumors, but tumor cells develop resistance toward drugs after a long period of chemotherapy. Interestingly, the gene expression of resistant cells usually generates increased sialic acid and raises the negative potential of the cell membranes, which is potentially useful to design novel theranostic models. In this work, we demonstrate multidrug resistant tumors-aimed theranostics by the virtue of the strong electrostatic attraction between resistant cells and nanomaterials. Human oral epithelial carcinoma vincristine-resistant tumor (KBV) and human oral epithelial carcinoma tumor (KB) were employed and compared as the tumor models. Polyethylene glycol-coated and Cu(ii) and vincristine codoped polyaniline nanoshuttles (VCR-PEG-CuPani NSs), which possessed multifunctions, positive charges, and blood circulation half-life of 6.26 ± 0.16 h, were employed as the nanomaterials for performing the tumor theranostics. Because of the stronger electrostatic attraction with KBV than that with KB, VCR-PEG-CuPani NSs showed higher enrichment of 8.05 ± 0.39% ID g-1 for KBV and a lower value of 6.02 ± 0.22% ID g-1 for KB. The higher accumulation of VCR-PEG-CuPani NSs in KBV tumors further improved the efficacy of tumor theranostics, such as those using magnetic resonance imaging, chemotherapy, and photothermal therapy.

16.
J Phys Chem Lett ; : 5182-5188, 2019 Aug 22.
Artigo em Inglês | MEDLINE | ID: mdl-31424936

RESUMO

Carbon dots (CDs), as emerging luminescent nanomaterials, possess excellent but complex properties, bringing about extensive attention and a lot of controversy. In this Perspective, we put forward the concept of "carbonized polymer dots" and emphasize the important role of polymerization and carbonization during the formation of CDs. We explore the common characters and clarify the complicated relationship of CDs, based on the reasonable classification of graphene quantum dots, carbon quantum dots, and carbonized polymer dots. Moreover, different perspectives are provided for comprehensive analysis about the essence of CDs, including quantum dots, molecules, and polymers. The photoluminescence mechanism has been classified into molecule state, carbon core state, surface/edge state, and cross-link enhanced emission effect for further understanding of complicated phenomena.

18.
ACS Appl Mater Interfaces ; 11(29): 25730-25739, 2019 Jul 24.
Artigo em Inglês | MEDLINE | ID: mdl-31299144

RESUMO

Enhancement of permeability and the retention effect is one of the main pathways for the accumulation of nanomaterials in tumor sites, but poor cellular internalization and rapid clearance of nanomaterials always hamper the efficacy of imaging diagnosis and treatment. With the consideration of both high tumor accumulation and cellular internalization, positively charged nanomaterials can adhere to the tumor cell membrane by an electrostatic force, which is conducive to cellular internalization, but they are easily recognized and cleared during blood circulation. However, negatively charged nanomaterials show an enhanced stealth-like effect and possess a long blood circulation time, which is conducive to tumor accumulation. Therefore, in this work, on the basis of the shielding effect of citrate ions to positive charge and the protonation under an acidic tumor microenvironment, pH-sensitive sodium citrate-modified polyaniline nanoshuttles (NSs) with negative charge during blood circulation but positive charge in tumor sites are designed. With this hierarchical targeting strategy, the blood circulation half-life increases from 4.35 to 7.33 h, and the retention rate of NSs in tumors increases from 5.29 to 8.57% ID/g. Because the retention rate of NSs is increased, the magnetic resonance imaging resolution and signal intensity are significantly improved. A synergistic treatment of tumors is further achieved by means of photothermal therapy with laser irradiation and chemotherapy via heat-stimulated drug release.


Assuntos
Portadores de Fármacos , Nanoestruturas , Neoplasias Experimentais , Citrato de Sódio , Nanomedicina Teranóstica , Microambiente Tumoral/efeitos dos fármacos , Compostos de Anilina , Animais , Linhagem Celular Tumoral , Portadores de Fármacos/química , Portadores de Fármacos/farmacocinética , Portadores de Fármacos/farmacologia , Humanos , Camundongos , Camundongos Nus , Nanoestruturas/química , Nanoestruturas/uso terapêutico , Neoplasias Experimentais/tratamento farmacológico , Neoplasias Experimentais/metabolismo , Neoplasias Experimentais/patologia , Citrato de Sódio/química , Citrato de Sódio/farmacocinética , Citrato de Sódio/farmacologia
19.
Appl Biochem Biotechnol ; 189(3): 1007-1019, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31161382

RESUMO

A heterologous xylose utilization pathway, either xylose reductase-xylitol dehydrogenase (XR-XDH) or xylose isomerase (XI), is usually introduced into Saccharomyces cerevisiae to construct a xylose-fermenting strain for lignocellulosic ethanol production. To investigate the molecular basis underlying the effect of different xylose utilization pathways on the xylose metabolism and ethanol fermentation, transcriptomes of flocculating industrial strains with the same genetic background harboring different xylose utilization pathways were studied. A different source of xylA did not obviously affect the change of the strains transcriptome, but compared with the XR-XDH strain, several key genes in the central carbon pathway were downregulated in the XI strains, suggesting a lower carbon flow to ethanol. The carbon starvation caused by lower xylose metabolism in XI strains further influenced the stress response and cell metabolism of amino acid, nucleobase, and vitamin. Besides, the downregulated genes mostly included those involved in mitotic cell cycle and the cell division-related process. Moreover, the transcriptomes analysis indicated that the after integrate xylA in the δ region, the DNA and chromosome stability and cell wall integrity of the strains were affected to some extent. The aim of this was to provide some reference for constructing efficient xylose-fermenting strains.


Assuntos
Perfilação da Expressão Gênica , Indústrias , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Xilose/metabolismo , DNA Recombinante/genética , Fermentação , Fatores de Transcrição/metabolismo
20.
ACS Appl Mater Interfaces ; 11(26): 23495-23502, 2019 Jul 03.
Artigo em Inglês | MEDLINE | ID: mdl-31252475

RESUMO

BiVO4 nanomaterials are potentially applicable in gas sensing, but the sensing performance is limited by the less active sites on the BiVO4 surface. In this work, we propose a strategy to improve the gas-sensing performance of BiVO4 by forming ultrathin nanosheets and introducing oxygen vacancies, which increase the surface active sites. Two-dimensional (2D) BiVO4 nanosheets with oxygen vacancies are prepared through a colloidal method with the assistance of nitric acid. Gas sensors based on the oxygen-defective 2D ultrathin BiVO4 nanosheets exhibit an enhanced sensing response, which is 3.4 times higher than those of the sensors based on oxygen-abundant BiVO4 nanosheets. The density functional theory calculation is employed to uncover the promoting effects of oxygen vacancies on enhancing the O2 adsorption capability of BiVO4 nanosheets. This work is not only expected to build a wide range of 2D metal oxide semiconductors with a high gas-sensing performance but also gives an insight into the mechanism of the enhanced response induced by the oxygen vacancies, which will be a guideline for further designing high-performance sensing materials.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA